The present invention relates to a device for introducing fuel into industrial furnaces (including boilers) fired by spreader stokers, fluidized bed combustion, and like technologies, and more particularly to an oscillating damper and an air-swept distributor.
Most fuel distributing devices in use today are of the mechanical or mechanical/pneumatic type. Such mechanical distributors use rotating shafts, blades or paddles to propel fuel into a furnace. Although mechanical distributors work adequately, they suffer the disadvantage of having many moving parts which are exposed to the heated furnace and thus present maintenance problems.
Pneumatic and mechanical/pneumatic systems, such as those having air-swept spout configurations, have been used for the incineration of refuse. Typically in these systems, a pneumatic distributor is attached to a metering device, which is remotely located and allows fuel consisting of coal, refuse, wood chips, or any mixture thereof to fall on an air-swept plate. The air sweeping over the plate pushes the fuel into the furnace. In the past, air supplies with a constant pressure have been used, tending to distribute the fuel at one area on the stoker and leading to inefficient combustion.
Attempts to more evenly distribute the fuel on the stoker have employed rotating valve dampers to vary the air pressure. The use of such rotating valve dampers has lead to fuel being distributed more evenly, but has resulted in a tendency of the fuel to collect toward the rear of the stoker, and thus has not effectively solved the problem of inefficient combustion. This is due largely to the inability to completely control the air flow and to the changing consistency of the fuel. Attempts to compensate for these factors by changing the elevation of the air-swept plate have frequently led merely to changes in the trajectory of the fuel but with no significant improvement in fuel distribution.
One of the primary objects of the present invention is to provide an even distribution of fuel over a stoker by providing a fully controllable air supply and air-swept distributor combination, thus optimizing the combustion process.
A fuel distribution system for distributing fuel into a furnace, in accordance with the invention includes at least one oscillating damper having a first body, a pivotal valve member mounted on the first body for oscillation about an axis, and a control mechanism attached to the valve member for controlling the oscillation of said valve member, thereby controllably adjusting the flow of air through said first body and to effect a throttling of the air flow. The system also includes at least one air-swept distributor having a second body, a trajectory plate pivotally attached to the second body for controlling the distribution of fuel into the furnace, a feature for directing air across the plate, with the directed air being operable to controllably blow the fuel across the plate and thereby further provide a controllable distribution of fuel into the furnace. In addition, the system includes an air conducting apparatus for communicating air from said oscillating damper to said air-swept distributor.
Other advantages and features will become apparent from the following description and claims, taken in connection with the accompanying drawings .